Your chickens should be able to handle those temps standing on their heads. After a week of spending days out there, I see no problem with moving them out there full time, if that's where their coop is.
If you need to get them out of your dining room, can you find a transitional space for them that would be cooler, but still not as cold as being at the mercy of outside temperatures would be?
How about a service porch or basement or an enclosed front porch. Somewhere that you can rig up a 100...